I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

"Kate" wrote in message
...
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better to
leave it open a tad?


Properly designed, modern units can handle a 10-15% blockage of discharge
air. So if that furnace has 10 total vents closing one is no big deal.

It might whistle a little if it is on the high flow side of the plenum. If
it does you may want to reconsider.

If it is an older system or you experience any noticeable change you can
open it back up. It isn't going to kill the system on a trial basis no
matter what. The worst thing that can happen is the furnace will shut down
via the high limit switch.

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Can you move the sofa?

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

Move the sofa, is cheaper?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

What about the sofa?

Expert advice: cost more! G

On Feb 2, 8:53�pm, Oren wrote:
On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Can you move the sofa?

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

Move the sofa, is cheaper?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

What about the sofa?

Expert advice: cost more! G

or put the sofa on small platform where legs are raising sofa ainch or
two so air can still flow

older folks will love the higher sofa, easier to get up and down

On Mon, 2 Feb 2009 18:00:13 -0800 (PST), "
wrote:

older folks will love the higher sofa, easier to get up and down

You can tell me! Are you having sex; at your age, on the sofa - don't
answer, but you can explain.

Thank you very much for taking the time to help.

Kate

Colbyt wrote:
"Kate" wrote in message
...
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better to
leave it open a tad?


Properly designed, modern units can handle a 10-15% blockage of discharge
air. So if that furnace has 10 total vents closing one is no big deal.

It might whistle a little if it is on the high flow side of the plenum. If
it does you may want to reconsider.

If it is an older system or you experience any noticeable change you can
open it back up. It isn't going to kill the system on a trial basis no
matter what. The worst thing that can happen is the furnace will shut down
via the high limit switch.

Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Kate, you might consider getting a long deflector for the register under
your sofa. For example:

http://www.improvementscatalog.com/h...deflector.html

"Use the heat register deflector to channel the heat into your room and
not into the bottom of the couch. Our PVC air register deflectors sit
over the register and re-direct the cooled or heated air from under the
furniture. Simply place air register deflectors over the register. The
air register deflectors click securely onto the floor register and
extend from 22" to 37" bringing the air out from under your chair,
couch, bed, cabinet, curtains or end table.

"The heat register deflector is a 2-piece unit 11-1/4" wide and 1-1/2"
high to deflect air discretely. The air register deflectors come with
one long clip to lock onto the register and two short clips to lock the
desired length."

I have some of these leftover. I had placed one under my sofa, but the
skirt on the sofa looked funny then. But, someone else on this
newsgroup suggested putting the sofa on blocks a bit. I will try this
and then install the deflector. Many thanks.

Kate

Erma1ina wrote:
Kate wrote:
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Kate, you might consider getting a long deflector for the register under
your sofa. For example:

http://www.improvementscatalog.com/h...deflector.html

"Use the heat register deflector to channel the heat into your room and
not into the bottom of the couch. Our PVC air register deflectors sit
over the register and re-direct the cooled or heated air from under the
furniture. Simply place air register deflectors over the register. The
air register deflectors click securely onto the floor register and
extend from 22" to 37" bringing the air out from under your chair,
couch, bed, cabinet, curtains or end table.

"The heat register deflector is a 2-piece unit 11-1/4" wide and 1-1/2"
high to deflect air discretely. The air register deflectors come with
one long clip to lock onto the register and two short clips to lock the
desired length."

On Feb 2, 10:08�pm, Oren wrote:
On Mon, 2 Feb 2009 18:00:13 -0800 (PST), "

wrote:
older folks will love the higher sofa, easier to get up and down

You can tell me! Are you having sex; at your age, on the sofa - don't
answer, but you can explain.

funny.

but for other elderly family members I put sofas and chairs, and a
couple beds on platforms so the elderly could still stand up....


my high school buddy did this for his wife after she ..had knee
surgery.

On Feb 3, 1:33*am, Kate wrote:
I have some of these leftover. *I had placed one under my sofa, but the
skirt on the sofa looked funny then. *But, someone else on this
newsgroup suggested putting the sofa on blocks a bit. *I will try this
and then install the deflector. *Many thanks.

Kate



Erma1ina wrote:
Kate wrote:
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Kate, you might consider getting a long deflector for the register under
your sofa. For example:

http://www.improvementscatalog.com/h...2923067-heat-r...

"Use the heat register deflector to channel the heat into your room and
not into the bottom of the couch. Our PVC air register deflectors sit
over the register and re-direct the cooled or heated air from under the
furniture. Simply place air register deflectors over the register. The
air register deflectors click securely onto the floor register and
extend from 22" to 37" bringing the air out from under your chair,
couch, bed, cabinet, curtains or end table.

"The heat register deflector is a 2-piece unit 11-1/4" wide and 1-1/2"
high to deflect air discretely. The air register deflectors come with
one long clip to lock onto the register and two short clips to lock the
desired length."- Hide quoted text -

- Show quoted text -


The real question here is what's the point to closing it off? The
heat you get out of it eventually makes it's way into the room. If
the room was too hot relative to other rooms, or the sofa is getting
hot, then it would make sense to try to balance it. But if it's ok
in that respect, then I don't see any issue with leaving it open.

On Feb 2, 4:53*pm, Kate wrote:
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Mmmmm, sofa with heat register right under it . . . sounds like a nice
nap sofa. -- H

"Bubba" wrote in message
...
On Mon, 2 Feb 2009 19:33:49 -0500, "Colbyt"
wrote:

Properly designed, modern units can handle a 10-15% blockage of discharge
air. So if that furnace has 10 total vents closing one is no big deal.

Ive been in the hvac business almost 30 yrs now colbyt.
Could you please point me to where you read that: "modern units can
handle a 10-15% blockage of discharge air."
Im not arguing that you cant close one register. I want to know where
you pulled that number from.

Bubba



That would be a quote from a certified engineer who was working on
redesigning some systems a few year back so "modern" is a relative term.

I do agree that excessive high limit shutdowns can cause problems with the
modern tin heat exchangers.

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...deflector.html

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...deflector.html


There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...7&context=lbnl

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...deflector.html

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...7&context=lbnl

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

On Sat, 07 Feb 2009 21:49:28 GMT, Erma1ina
wrote:

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...deflector.html

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...7&context=lbnl

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

I did read it, and I did understand it. And what's more I can test
the static pressure in my system if I want to. I know how and caould
make the required test equipment very quick;y and cheaply.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

Fully understood.

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

And the airflow change (which can be tetermined by the pressure
change) is all we need to know to know if there will be a problem.
Accorsing to the information shown in the graphs included, it is
obvious it is not going to cause a problem unless there are fewer than
something like 5 outlets and you block one.
In my house there are mo less than 12. For most of the time I have
owned the house (26 years - 20 with the original (at that time 8 yr
old) furnace) at least 2 of those registers were completely closed,
one has been under/behind a couch, and 2 are shut off about half the
time when 2 bedrooms are not needed (daughters not home).

Add to that the FACT that many homes have balancing dampers installed
in the branch runners - my house has at least 3 (exposed in the
finished basement) Two of them are set to about 2/3 flow (on the six
inch pipes heading to the upstairs of the 2 story) to restrict the
flow to the upstairs so enough heat gets into the main floor.

This was all checked when the new furnace was installed about 7 years
ago, and the plenum pressure/airflow was all well within the specified
parameters. Both the pressure difference across the exchanger, the
heat rize across the exchanger, as well as the pressure in the plenum
was checked, and all were well within limits.
I don't have the pressure numbers but IIRC both pressure readings were
well under an inch of water.with the fan speed adjusted for the
desired heat rize. The installer did say the ducting was "generous".

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

wrote:

On Sat, 07 Feb 2009 21:49:28 GMT, Erma1ina
wrote:

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...deflector.html

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...7&context=lbnl

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

I did read it, and I did understand it. And what's more I can test
the static pressure in my system if I want to. I know how and caould
make the required test equipment very quick;y and cheaply.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

Fully understood.

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

And the airflow change (which can be tetermined by the pressure
change) is all we need to know to know if there will be a problem.
Accorsing to the information shown in the graphs included, it is
obvious it is not going to cause a problem unless there are fewer than
something like 5 outlets and you block one.
In my house there are mo less than 12. For most of the time I have
owned the house (26 years - 20 with the original (at that time 8 yr
old) furnace) at least 2 of those registers were completely closed,
one has been under/behind a couch, and 2 are shut off about half the
time when 2 bedrooms are not needed (daughters not home).

Add to that the FACT that many homes have balancing dampers installed
in the branch runners - my house has at least 3 (exposed in the
finished basement) Two of them are set to about 2/3 flow (on the six
inch pipes heading to the upstairs of the 2 story) to restrict the
flow to the upstairs so enough heat gets into the main floor.

This was all checked when the new furnace was installed about 7 years
ago, and the plenum pressure/airflow was all well within the specified
parameters. Both the pressure difference across the exchanger, the
heat rize across the exchanger, as well as the pressure in the plenum
was checked, and all were well within limits.
I don't have the pressure numbers but IIRC both pressure readings were
well under an inch of water.with the fan speed adjusted for the
desired heat rize. The installer did say the ducting was "generous".

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

For Pete's sake, just admit you didn't understand the study YOU cited.
Stop trying to kick up a bunch of dust in a lame attempt to obscure that
fact.

On Feb 2, 4:53*pm, Kate wrote:
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Furnaces have a heat temp range, there is a maximum design temp for
the exchanger in your manual. Exceeding it lowers efficiency and and
most likely furnace life. It can also give you uneven heat and shorter
cycling. When the exchanger goes it is an expensive new exchanger, or
you opt for a new and maybe more efficient unit. You dont know if the
units ducts are undersized and that you may already be at its maximum
temp. One register isnt much if you have 30 but it is smartest to know
what temp you are at just above the exchanger to know what leeway you
have before closing down supplys, closing a supply restricts air and
raises the temp of the furnace. My temp was to high, I had it lowered
and heat was more even and comfortable.

On Feb 8, 1:35*am, Erma1ina wrote:
wrote:

On Sat, 07 Feb 2009 21:49:28 GMT, Erma1ina
wrote:

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...2923067-heat-r...

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent..
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm *at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. *Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...le=3527&contex...

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

*I did read it, and I did understand it. And what's more I can test
the static pressure in my system if I want to. I know how and caould
make the required test equipment very quick;y and cheaply.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

Fully understood.

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

And the airflow change (which can be tetermined by the pressure
change) is all we need to know *to know if there will be a problem.
Accorsing to the information shown in the graphs included, it is
obvious it is not going to cause a problem unless there are fewer than
something like 5 outlets and you block one.
In my house there are mo less than 12. For most of the time I have
owned the house (26 years - 20 with the original (at that time 8 yr
old) furnace) at least 2 of those registers were completely closed,
one has been under/behind a couch, and 2 are shut off about half the
time when 2 bedrooms are not needed (daughters not home).

Add to that the FACT that many homes have balancing *dampers installed
in the branch runners - my house has at least 3 (exposed in the
finished basement) Two of them are set to about 2/3 flow (on the six
inch pipes heading to the upstairs of the 2 story) to restrict the
flow to the upstairs so enough heat gets into the main floor.

This was all checked when the new furnace was installed about 7 years
ago, and the plenum pressure/airflow was all well within the specified
parameters. Both the pressure difference across the exchanger, the
heat rize across the exchanger, as well as the pressure in the plenum
was checked, and all were well within limits.
I don't have the pressure numbers but IIRC both pressure readings were
well under an inch of water.with the fan speed adjusted for the
desired heat rize. The installer did say the ducting was "generous".

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

For Pete's sake, just admit you didn't understand the study YOU cited.
Stop trying to kick up a bunch of dust in a lame attempt to obscure that
fact.- Hide quoted text -

- Show quoted text -


It sounds to me like he understood what he cited perfectly well.
BTW, if it's so damn bad to close a couple of registers, why do the
vast majority of homes have them? New construction here has
virtually every output register with a closeable flap and user
operated lever.

"Bubba" wrote in message

and do you actually know trader, that if all duct systems were
properly sized and installed, you would not need a closeable flap on
them. Unfortunately, most systems are installed by the lowest bidder.
Its all driven by the builder. He builds the home, hires the lowest
bidding subs and profits at the highest sale price. This process
happens in some of the least expensive and most expensive homes
around.
Bubba

But what constitutes properly sized. You may want a bedroom warm and comfy
while I like it cool to sleep. Thus the reason to have those closeable
flaps. One size does not fit all no matter who does the install.

On Feb 8, 7:58*am, Bubba wrote:
On Sun, 8 Feb 2009 03:17:16 -0800 (PST), ransley





wrote:
On Feb 2, 4:53*pm, Kate wrote:
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Furnaces have a heat temp range, there is a maximum design temp for
the exchanger in your manual. Exceeding it lowers efficiency and and
most likely furnace life. It can also give you uneven heat and shorter
cycling. When the exchanger goes it is an expensive new exchanger, or
you opt for a new and maybe more efficient unit. You dont know if the
units ducts are undersized and that you may already be at its maximum
temp. One register isnt much if you have 30 but it is smartest to know
what temp you are at just above the exchanger to know what leeway you
have before closing down supplys, closing a supply restricts air and
raises the temp of the furnace. My temp was to high, I had it lowered
and heat was more even and comfortable.

Spoken from a true idiot (ransley) who has no formal training in hvac
and thinks that just turning down the gas pressure is an acceptable
practice. Please ignore any of his babbeling statements.
Bubba- Hide quoted text -

- Show quoted text -

There you go, missquote me. I said I had it done, Re-Read it. I had
the blower speed raised by my installer, put in 3 basement supplys, 1
new return, and increased 2 returns sizing. Now I have a low enough
exchanger temp to balance all I want. I did not recomend anything
unsafe. Is life that lonely Bubba that you now need to make up crap to
feed your ego. Lets drop it Bubba, call it a permanent truce, this is
just a waste between us and group disruptive to all. Tell you what, I
will be respectfull of you and you do the same.

wrote:

On Feb 8, 1:35 am, Erma1ina wrote:
wrote:

On Sat, 07 Feb 2009 21:49:28 GMT, Erma1ina
wrote:

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...2923067-heat-r...

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...le=3527&contex...

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

I did read it, and I did understand it. And what's more I can test
the static pressure in my system if I want to. I know how and caould
make the required test equipment very quick;y and cheaply.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

Fully understood.

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

And the airflow change (which can be tetermined by the pressure
change) is all we need to know to know if there will be a problem.
Accorsing to the information shown in the graphs included, it is
obvious it is not going to cause a problem unless there are fewer than
something like 5 outlets and you block one.
In my house there are mo less than 12. For most of the time I have
owned the house (26 years - 20 with the original (at that time 8 yr
old) furnace) at least 2 of those registers were completely closed,
one has been under/behind a couch, and 2 are shut off about half the
time when 2 bedrooms are not needed (daughters not home).

Add to that the FACT that many homes have balancing dampers installed
in the branch runners - my house has at least 3 (exposed in the
finished basement) Two of them are set to about 2/3 flow (on the six
inch pipes heading to the upstairs of the 2 story) to restrict the
flow to the upstairs so enough heat gets into the main floor.

This was all checked when the new furnace was installed about 7 years
ago, and the plenum pressure/airflow was all well within the specified
parameters. Both the pressure difference across the exchanger, the
heat rize across the exchanger, as well as the pressure in the plenum
was checked, and all were well within limits.
I don't have the pressure numbers but IIRC both pressure readings were
well under an inch of water.with the fan speed adjusted for the
desired heat rize. The installer did say the ducting was "generous".

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

For Pete's sake, just admit you didn't understand the study YOU cited.
Stop trying to kick up a bunch of dust in a lame attempt to obscure that
fact.- Hide quoted text -

- Show quoted text -

It sounds to me like he understood what he cited perfectly well.
BTW, if it's so damn bad to close a couple of registers, why do the
vast majority of homes have them? New construction here has
virtually every output register with a closeable flap and user
operated lever.

And "what he cited" did not address the OP issue: whether closing
registers could damage the furnace. The study he cited, without
understanding, did NOT ADDRESS THAT ISSUE.

Clear enough for you, idiot... ?!

OK - I just hiooked up a "sensitive manometer" to my furnace duct.On
Sun, 08 Feb 2009 06:35:38 GMT, Erma1ina
wrote:

wrote:

On Sat, 07 Feb 2009 21:49:28 GMT, Erma1ina
wrote:

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...deflector.html

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...7&context=lbnl

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

I did read it, and I did understand it. And what's more I can test
the static pressure in my system if I want to. I know how and caould
make the required test equipment very quick;y and cheaply.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

Fully understood.

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

And the airflow change (which can be tetermined by the pressure
change) is all we need to know to know if there will be a problem.
Accorsing to the information shown in the graphs included, it is
obvious it is not going to cause a problem unless there are fewer than
something like 5 outlets and you block one.
In my house there are mo less than 12. For most of the time I have
owned the house (26 years - 20 with the original (at that time 8 yr
old) furnace) at least 2 of those registers were completely closed,
one has been under/behind a couch, and 2 are shut off about half the
time when 2 bedrooms are not needed (daughters not home).

Add to that the FACT that many homes have balancing dampers installed
in the branch runners - my house has at least 3 (exposed in the
finished basement) Two of them are set to about 2/3 flow (on the six
inch pipes heading to the upstairs of the 2 story) to restrict the
flow to the upstairs so enough heat gets into the main floor.

This was all checked when the new furnace was installed about 7 years
ago, and the plenum pressure/airflow was all well within the specified
parameters. Both the pressure difference across the exchanger, the
heat rize across the exchanger, as well as the pressure in the plenum
was checked, and all were well within limits.
I don't have the pressure numbers but IIRC both pressure readings were
well under an inch of water.with the fan speed adjusted for the
desired heat rize. The installer did say the ducting was "generous".

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

For Pete's sake, just admit you didn't understand the study YOU cited.
Stop trying to kick up a bunch of dust in a lame attempt to obscure that
fact.




OK - I just hooked up a "sensitive manometer" to my furnace duct.
Zeroed with the furnace shut off, at 600cfm (the low constant speed)
there is no reading on the manometer. With it on normal blower speed
for heating (900cfm I believe - might be 1200)) with all registers
except the covered on in the bedroom open, there is still no reading
on the manometer. When I close 3 more registers I get about 0.15
inches on the manometer. I'd accept an error of 0.1" at zero, meaning
I MIGHT be getting up to 0.25" WC with 3/13ths (23.1%) of the outlets
closed.

The air temperature rise across the heat exchanger changes 2 degrees C
on 35000 BTU output, and aprox 4 degrees C at 50,000 BTU output.
This is a two stage 35000/50,000 BTU 80% efficiency NTV6050 ICP
(Tempstar) furnace feeding a 9X17 hot air duct with 9 takeoffs from
it, 7X 5 inch and 2X4", and a total of 14 ( I just counted them)
outlets and 3 cold air returns (one on each floor). With one
permanently closed I'm making my calcs as having 13 and closing 3-

Test equipment is a 45 degree water manometer (meaning 1 inch change
in water level in the tube is equal to .5 inch WC pressure change) and
2 thermocouple temperature guages with 0-999 display accurate to the
neerest degree C.
I am fammiliar with the operation of both instruments and repeated the
experiments 3 times with discrepencies well below 10% error highest to
lowest.

Plenum output temps at 50KBTU were 65 degrees C and at 35KBTU 46
degrees C with the outlets all open and ambient (cold air return) at a
nominal 20 degrees C. Ratio of 45:26= 1.73:1
If the rated BTU output was accurate, the temperature change would be
predicted to be 50:35 = 1.43:1, so we do not have a gross error which
would indicate a seriously flawed methodology.
I think this has pretty well put the question to bed. If closing off
almost 1/4 of the airflow only raises the output temperatures and heat
rise across the heat exchanger by 4 degreec C at high output and 2
degrees C at low output, closing ONE register is NOT going to damage
the furnace heat exchanger. In my case, 1 closed instead of 3 would
produce approxemately ONE degree difference at 50KBTU with a 900 (or
possibly 1200) CFM blower.

On Sun, 08 Feb 2009 08:56:27 -0500, Bubba
wrote:

On Sun, 8 Feb 2009 05:28:55 -0800 (PST), wrote:

On Feb 8, 1:35Â*am, Erma1ina wrote:
wrote:

On Sat, 07 Feb 2009 21:49:28 GMT, Erma1ina
wrote:

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...2923067-heat-r...

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm Â*at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Â*Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...le=3527&contex...

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

Â*I did read it, and I did understand it. And what's more I can test
the static pressure in my system if I want to. I know how and caould
make the required test equipment very quick;y and cheaply.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

Fully understood.

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

And the airflow change (which can be tetermined by the pressure
change) is all we need to know Â*to know if there will be a problem.
Accorsing to the information shown in the graphs included, it is
obvious it is not going to cause a problem unless there are fewer than
something like 5 outlets and you block one.
In my house there are mo less than 12. For most of the time I have
owned the house (26 years - 20 with the original (at that time 8 yr
old) furnace) at least 2 of those registers were completely closed,
one has been under/behind a couch, and 2 are shut off about half the
time when 2 bedrooms are not needed (daughters not home).

Add to that the FACT that many homes have balancing Â*dampers installed
in the branch runners - my house has at least 3 (exposed in the
finished basement) Two of them are set to about 2/3 flow (on the six
inch pipes heading to the upstairs of the 2 story) to restrict the
flow to the upstairs so enough heat gets into the main floor.

This was all checked when the new furnace was installed about 7 years
ago, and the plenum pressure/airflow was all well within the specified
parameters. Both the pressure difference across the exchanger, the
heat rize across the exchanger, as well as the pressure in the plenum
was checked, and all were well within limits.
I don't have the pressure numbers but IIRC both pressure readings were
well under an inch of water.with the fan speed adjusted for the
desired heat rize. The installer did say the ducting was "generous".

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

For Pete's sake, just admit you didn't understand the study YOU cited.
Stop trying to kick up a bunch of dust in a lame attempt to obscure that
fact.- Hide quoted text -

- Show quoted text -


It sounds to me like he understood what he cited perfectly well.
BTW, if it's so damn bad to close a couple of registers, why do the
vast majority of homes have them? New construction here has
virtually every output register with a closeable flap and user
operated lever.

and do you actually know trader, that if all duct systems were
properly sized and installed, you would not need a closeable flap on
them. Unfortunately, most systems are installed by the lowest bidder.
Its all driven by the builder. He builds the home, hires the lowest
bidding subs and profits at the highest sale price. This process
happens in some of the least expensive and most expensive homes
around.
Bubba


Which is why on a proerly designed and set up forced air heating
system you will generally find the main plenum/duct gets smaller the
farther it gets from the furnace, and not all heating duncts coming
off that main duct are the same size, AND there are balancing dampers
in at least several of those "take-off" ducts heading to various parts
of the house to balance the air flow.

In cheap contract housing you seldom see these features.

That said, if you don't want your bedroom, for instance, as warm as
the nursery or the livingroom, you partially (or fully) close off the
heat flow to that room. (whether the system was properly designed or
not)

On Sun, 08 Feb 2009 19:01:46 GMT, Erma1ina
wrote:

wrote:

On Feb 8, 1:35 am, Erma1ina wrote:
wrote:

On Sat, 07 Feb 2009 21:49:28 GMT, Erma1ina
wrote:

wrote:

On Fri, 06 Feb 2009 22:51:46 -0500, wrote:

On Mon, 02 Feb 2009 14:53:10 -0800, Kate wrote:

I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Why don't you just deflect it with an extent ion like this:

http://www.improvementscatalog.com/h...2923067-heat-r...

There are two registers in my bedroom BECAUSE the dresser is over one.
You guys saying it being blocked is going to damage my furnace?

All closing one or two registers is going to do is make the rooms with
the closed registers cold and make the other registers in the house
provide a little more air. By blocking one 4" pipe out of ten you are
NOT reducing the flow by ten percent. Not likely even by two percent.
The pressure in the plenum will possibly go up .1 of an inch of water
The blowers are generally rated at 1200-1700cfm at .3 inches water
column pressure.
Doubling the static pressure reduced the efficiency of the blower by
half. - not the delivery, but the efficiency in CFM/watt. The average
furnace fan is 10-15% efficient, and produces something like 2
cfm/watt. Actual airflow dropped by one third when plenum pressure
was doubled from .6" to 1.3"
In a study of furnace installations, plenum pressures were in the
range of .25 to 1.9".
That same test shows that a brushless PM blower motor is SIX times as
efficient as an AC split cap motor at low speeds (used in constant
flow systems extensively here in Canada). This amounts to a 74%
savings in electricity used by the furnace - and as much as 25% of
whole house use. The loss of heat output from the inefficient fan
motor increases the gas consumption by 14%.
(I guess that's why I didn't see ANY gas savings when I put in the new
Medium efficiency (80+%) furnace but saw a huge difference in
electrical consumption!!!

If you doubt what I'm reporting you can read the report yourself at
http://repositories.cdlib.org/cgi/vi...le=3527&contex...

The test was done under the auspices of the Ernest Orlando Lawrence
Berkeley National Laboratory at the University of California by Ian
Walker and Jim Lutz. for the California Energy Commission and the US
Department of energy.

VERY interesting reading if you are into that type of thing.

Apparently YOU did NOT READ this research draft.

I did read it, and I did understand it. And what's more I can test
the static pressure in my system if I want to. I know how and caould
make the required test equipment very quick;y and cheaply.

I suggest you DO READ page 13 wherein the TEST SETUP is described.
Here's an excerpt pertinent to the issue of whether a furnace can be
damaged by blocking heat registers:

"The burners did not operate during the test and no gas was hooked up.
No cooling coils or filters were installed. In real field installations
the cooling coils and filters will act as additional flow resistance
leading to increased pressures across the blowers."

Fully understood.

In other words, ONLY the air-handling characteristics of the furnace
BLOWERS were being examined in the test reported in this study, NOT the
heat characteristics of the furnace and their effects.

And the airflow change (which can be tetermined by the pressure
change) is all we need to know to know if there will be a problem.
Accorsing to the information shown in the graphs included, it is
obvious it is not going to cause a problem unless there are fewer than
something like 5 outlets and you block one.
In my house there are mo less than 12. For most of the time I have
owned the house (26 years - 20 with the original (at that time 8 yr
old) furnace) at least 2 of those registers were completely closed,
one has been under/behind a couch, and 2 are shut off about half the
time when 2 bedrooms are not needed (daughters not home).

Add to that the FACT that many homes have balancing dampers installed
in the branch runners - my house has at least 3 (exposed in the
finished basement) Two of them are set to about 2/3 flow (on the six
inch pipes heading to the upstairs of the 2 story) to restrict the
flow to the upstairs so enough heat gets into the main floor.

This was all checked when the new furnace was installed about 7 years
ago, and the plenum pressure/airflow was all well within the specified
parameters. Both the pressure difference across the exchanger, the
heat rize across the exchanger, as well as the pressure in the plenum
was checked, and all were well within limits.
I don't have the pressure numbers but IIRC both pressure readings were
well under an inch of water.with the fan speed adjusted for the
desired heat rize. The installer did say the ducting was "generous".

Blocking supply registers can result in damage to a furnace by
decreasing the heat dissipation from the heat exchanger and its
environs.

For Pete's sake, just admit you didn't understand the study YOU cited.
Stop trying to kick up a bunch of dust in a lame attempt to obscure that
fact.- Hide quoted text -

- Show quoted text -

It sounds to me like he understood what he cited perfectly well.
BTW, if it's so damn bad to close a couple of registers, why do the
vast majority of homes have them? New construction here has
virtually every output register with a closeable flap and user
operated lever.

And "what he cited" did not address the OP issue: whether closing
registers could damage the furnace. The study he cited, without
understanding, did NOT ADDRESS THAT ISSUE.

Clear enough for you, idiot... ?!
ANd for anyone who DOES understand, it addresses it very clearly.

On Sun, 8 Feb 2009 03:17:16 -0800 (PST), ransley
wrote:

On Feb 2, 4:53Â*pm, Kate wrote:
I have a Trane furnace.

One of the heat registers in my livingroom is underneath my sofa.
There are two registers in that room.

Is it safe to completely close off the register, or would it be better
to leave it open a tad?

I am not sure if this could damage my unit, and thought I would get some
expert advice here.

Many thanks.

Kate

Furnaces have a heat temp range, there is a maximum design temp for
the exchanger in your manual. Exceeding it lowers efficiency and and
most likely furnace life. It can also give you uneven heat and shorter
cycling. When the exchanger goes it is an expensive new exchanger, or
you opt for a new and maybe more efficient unit. You dont know if the
units ducts are undersized and that you may already be at its maximum
temp. One register isnt much if you have 30 but it is smartest to know
what temp you are at just above the exchanger to know what leeway you
have before closing down supplys, closing a supply restricts air and
raises the temp of the furnace. My temp was to high, I had it lowered
and heat was more even and comfortable.

There are 4 limit switches listed as possibilities on my furnace -
180, 190, 230, and 260 degrees F. That temperature is taken on the
wall of the heat exchanger plenum.
With 180 being the LOWEST, which is 82.2F, and 260 being the highest
(being 126C) the plenum temps in the 60 - 70 degree C range are
defineitey safe.